The death toll from pancreatic cancer goes on increasing year by year, and is ranked high in the worldwide cause-specific statistics of cancer death. However, there are very few effective treatment methods for pancreatic cancer, and, as an almost only treatment method for which a complete cure can be expected, surgical excision of a cancerous part has been conducted. In addition, also for bile duct cancer, when cancer development or metastasis is recognized at the junction with the pancreas, simultaneous excision of the pancreas is selected.
At the moment, the number of such surgeries of pancreas excision reaches about 40,000 in the United States, and also, 10,000 or more in Japan. However, it has been reported that a mortality rate after surgeries reaches several percent even in an experienced medical facility, and that the mortality rate is further increased in cases of medical doctors less-experienced in surgeries. As one of the causes, “pancreatic fluid leakage” in which the pancreatic fluid leaks from a pancreas section after pancreas excision can be mentioned. When the pancreatic fluid leakage occurs, there is a risk that not only bacterial infections are caused, but also blood vessels are digested by a self-digestion action of the pancreatic fluid, causing serious bleeding and thus resulting in death (NPL 1). Therefore, pancreatic fluid leakage has been the most important issue in pancreatectomies. Although various pancreatectomy techniques and postoperative management techniques have been studied in order to prevent occurrence of pancreatic fluid leakage and its intensification, pancreatic fluid leakage still occurs at a frequency of 30% to 50%.
Factors that make it difficult to prevent pancreatic fluid leakage are as follows: not only is it difficult to carry out a ligature treatment to all stumps of pancreatic ducts because normal pancreatic ducts are very thin, and therefore, are difficult to identify, but also there is no technique which can visualize leakage of colorless and transparent pancreatic fluid during surgeries. At the moment, measurement on a concentration of amylase, which is a glycolytic enzyme in an intraperitoneal drainage fluid, the measurement proposed by ISGPF (International study group on pancreatic fistula), has been used as a technique for detecting pancreatic fluid leakage (NPLs 2 and 3). However, this technique not only requires time until acquisition of detection results, but also does not directly measure a protease, which is considered to act a major role in the above-described self-digestion action of the pancreatic fluid, causing serious complications after surgeries, and therefore, it has been pointed out that the technique does not always accurately reflect seriousness of the pancreatic fluid leakage after surgeries (NPLs 4 and 5).
Because of such circumstances, it has been strongly desired to establish a novel method of detecting pancreatic fluid leakage for identifying pancreatic ducts and for quickly and appropriately confirming leakage of pancreatic fluid during surgeries, as an alternative to the conventional method by the measurement of an amylase concentration.